Electric control of magnetic properties, or inversely, magnetic control of dielectric properties in solids, is called a magnetoelectric effect and has long been investigated from the point of view of both fundamental physics and potential application. Magnetic and dielectric properties usually show minimal coupling, but it recently has been discovered that magnetically induced ferroelectricity in some spiral magnets enables remarkably large and versatile magnetoelectric responses. To stabilize such helimagnetism, magnetic frustration (competition between different magnetic interactions) is considered the key. In the present work, two of the most typical frustrated spin systems-triangular lattice antiferromagnets and edge-shared chain magnets-have systematically been investigated. Despite the crystallographic simplicity of target systems, rich magnetoelectric responses are ubiquitously observed. The current results published here offer a useful guideline in the search for new materials with unique magnetoelectric functions, and also provide an important basis for a deeper understanding of magnetoelectric phenomena in more complex systems.

This brief reviews current research on magnetic skyrmions, with emphasis on formation mechanisms, observation techniques, and materials design strategies. The response of skyrmions, both static and dynamical, to various electromagnetic fields is also covered in detail. Recent progress in magnetic imaging techniques has enabled the observation of skyrmions in real space, as well as the analysis of their ordering manner and the details of their internal structure. In metallic systems, conduction electrons moving through the skyrmion spin texture gain a nontrivial quantum Berry phase, which provides topological force to the underlying spin texture and enables the current-induced manipulation of magnetic skyrmions. On the other hand, skyrmions in an insulator can induce electric polarization through relativistic spin-orbit interaction, paving the way for the control of skyrmions by an external electric field without loss of Joule heating. Because of its nanometric scale, particle nature, and electric controllability, skyrmions are considered as potential candidates for new information carriers in the next generation of spintronics devices.

Electric control of magnetic properties, or inversely, magnetic control of dielectric properties in solids, is called a magnetoelectric effect and has long been investigated from the point of view of both fundamental physics and potential application. Magnetic and dielectric properties usually show minimal coupling, but it recently has been discovered that magnetically induced ferroelectricity in some spiral magnets enables remarkably large and versatile magnetoelectric responses. To stabilize such helimagnetism, magnetic frustration (competition between different magnetic interactions) is considered the key. In the present work, two of the most typical frustrated spin systems-triangular lattice antiferromagnets and edge-shared chain magnets-have systematically been investigated. Despite the crystallographic simplicity of target systems, rich magnetoelectric responses are ubiquitously observed. The current results published here offer a useful guideline in the search for new materials with unique magnetoelectric functions, and also provide an important basis for a deeper understanding of magnetoelectric phenomena in more complex systems.